Ahmed Elmohamady's late header snatched three points to send Hull second in the Championship and deny stubborn Derby.
After a poor first-half display, Hull took the lead shortly after the break when substitute Gedo headed home with just his second touch of the ball.
Jamie Ward punished goalkeeper David Stockdale's mistake to put the visitors level with six minutes remaining.
But Elmohamady fired in from a corner before Derby's Gareth Roberts was sent off for a lunge on Nick Proschwitz.
It was a miserable end to an evening that began promisingly for a Derby side that enjoyed the better of the early exchanges.
They could not make their pressure count through as Conor Sammon poked wide and a last-ditch tackle by Jack Hobbs barred Ward's way to goal.
City sparked into life as the half ended with Stephen Quinn's near-post header skimming just wide of Adam Legzdins' right-hand post.
Egypt international Gedo's header was more precise as he nodded Robbie Brady's delivery back across the Derby goalkeeper for the opener.
The Egyptian came close to a second with a volley just over, but Derby pressed forward and Sammon thumped the underside of the bar before almost inadvertently turning in Ward's effort.
Ward's industry was rewarded when Stockdale spilled Craig Bryson's cross to gift him a simple tap-in.
But Derby were again undone in the air as Elmohamady converted from another Brady delivery before Roberts was dismissed and Proschwitz picked himself up to miss a fine chance to make the game safe.
VIEW FROM THE DRESSING ROOM
Hull manager Steve Bruce: "The boy Gedo showed his class. He's an international footballer and I think he's got 19 goals in 30 games so we know he has got quality.
"A big credit goes to the chairman. He's worked wonders to get him here.
"I didn't think it would be possible to get two international footballers on loan, and Ahmed Fathi will be a big player for us too."
Derby manager Nigel Clough:
"It would have been a thoroughly deserved point. It was a very good away performance at one of the favourites for promotion and I can't ask any more from our players whatsoever.
"That's two major decisions in four days that have gone against us.
"We don't usually appeal these things unless it's blatantly obvious, so I don't think we will be, but it certainly wasn't intentional."
- 34 Stockdale
- 05 Chester
- 06 Hobbs
- 15 McShane
- 08 Evans Booked (Rosenior - 90' )
- 10 Koren (Mohamed Gedo - 46' )
- 27 Elmohamady Booked
- 29 Quinn
- 31 Meyler Booked
- 11 Simpson (Proschwitz - 46' )
- 30 Brady
- 01 Jakupovic
- 02 Rosenior
- 17 Fathi
- 14 Cairney
- 16 Olofinjana
- 22 Mohamed Gedo
- 33 Proschwitz
- 13 Legzdins
- 02 Brayford
- 03 Roberts Dismissed
- 06 Keogh
- 23 Freeman (Robinson - 80' )
- 04 Bryson Booked
- 07 Coutts Booked (Buxton - 85' )
- 08 Hendrick
- 19 Hughes
- 10 Ward
- 32 Sammon (Jacobs - 73' Booked )
- 01 Fielding
- 05 Buxton
- 21 Gjokaj
- 22 Hoganson
- 12 Jacobs
- 18 Davies
- 11 Robinson
Live Text Commentary
Full Time The final whistle goes and the game is over.90:00 +4:33 Substitution
Substitution Corry Evans leaves the field to be replaced by Liam Rosenior.90:00 +3:24
Unfair challenge on Ahmed Elmohamady by Craig Bryson results in a free kick. Ahmed Elmohamady takes the direct free kick.90:00 +2:16
Mohamed Gedo takes a shot from 6 yards.88:32
Free kick taken by James Chester.88:32 Dismissal
Dismissal Gareth Roberts receives a red card.88:20
Nick Proschwitz fouled by Gareth Roberts, the ref awards a free kick.86:58 Booking
Booking Ahmed Elmohamady goes into the book.86:56
Robbie Brady provided the assist for the goal.86:56 Goal scored
Goal! - Ahmed Elmohamady - Hull City 2 - 1 Derby Ahmed Elmohamady finds the net with a headed goal from close in. Hull 2-1 Derby.86:14
The ball is swung over by Robbie Brady, John Brayford makes a clearance. Corry Evans takes a shot. Gareth Roberts gets a block in. Robbie Brady takes the inswinging corner,84:32 Substitution
Substitution Jake Buxton is brought on as a substitute for Paul Coutts.84:32
David Meyler takes a shot from deep inside the box clearing the bar.84:14
Foul by Gareth Roberts on Ahmed Elmohamady, free kick awarded. Free kick taken by Paul McShane.83:19
Assist by Jeff Hendrick.83:19 Goal scored
Goal! - Jamie Ward - Hull City 1 - 1 Derby Jamie Ward fires in a goal from inside the area to the bottom right corner of the goal. Hull 1-1 Derby.82:26
Foul by Nick Proschwitz on Michael Jacobs, free kick awarded. Paul Coutts crosses the ball in from the free kick, Nick Proschwitz makes a clearance. Jeff Hendrick sends in a cross,79:35
Direct effort from the free kick comes in from Robbie Brady.79:35 Substitution
Substitution Kieron Freeman leaves the field to be replaced by Theo Robinson.79:35
Unfair challenge on Mohamed Gedo by John Brayford results in a free kick.
David Stockdale takes the direct free kick.79:03 Booking
Booking Michael Jacobs is shown a yellow card for unsporting behaviour.78:48
Michael Jacobs concedes a free kick for a foul on Jack Hobbs.77:58
Unfair challenge on James Chester by Jeff Hendrick results in a free kick. David Stockdale restarts play with the free kick.72:26
Direct free kick taken by Gareth Roberts.72:26 Substitution
Substitution Michael Jacobs joins the action as a substitute, replacing Conor Sammon.72:26
Mohamed Gedo concedes a free kick for a foul on Gareth Roberts.71:33
Unfair challenge on Craig Bryson by Mohamed Gedo results in a free kick. Jamie Ward takes the direct free kick.71:01
Gareth Roberts sends in a cross, Jack Hobbs gets a block in.70:44
The ball is delivered by Robbie Brady, Richard Keogh makes a clearance.69:32
The assistant referee flags for offside against Conor Sammon. David Stockdale takes the indirect free kick.69:21
Nick Proschwitz concedes a free kick for a foul on John Brayford. John Brayford restarts play with the free kick.68:03
Jamie Ward takes a shot.66:56
Unfair challenge on Richard Keogh by Mohamed Gedo results in a free kick. Free kick taken by John Brayford.65:22
Jamie Ward crosses the ball, Conor Sammon takes a shot.61:22
Mohamed Gedo gives away a free kick for an unfair challenge on Jeff Hendrick. Free kick crossed right-footed by Jamie Ward from left wing, Ahmed Elmohamady manages to make a clearance.61:00
Jamie Ward takes a shot from 20 yards. Save by David Stockdale.60:26
David Meyler produces a curled left-footed shot from just outside the area that hits the post.55:11
David Meyler produces a cross, clearance by John Brayford.53:18
Jeff Hendrick concedes a free kick for a foul on Nick Proschwitz. David Meyler takes the free kick.50:13
The ball is swung over by Ahmed Elmohamady, Mohamed Gedo produces a right-footed shot from inside the area that goes over the bar.46:23
Assist on the goal came from Robbie Brady.46:23 Goal scored
Goal! - Mohamed Gedo - Hull City 1 - 0 Derby Mohamed Gedo finds the net with a headed goal from inside the penalty area. Hull 1-0 Derby.46:21
Robbie Brady crosses the ball,45:01
The referee starts the second half.45:01 Substitution
Substitution Jay Simpson leaves the field to be replaced by Nick Proschwitz.45:01 Substitution
Substitution (Hull) makes a substitution, with Mohamed Gedo coming on for Robert Koren.45:00 +2:53 Half time
Half Time The match has reached half-time.45:00 +1:54
Free kick crossed by Gareth Roberts, David Stockdale makes a save.45:00 +1:54 Booking
Booking Corry Evans is booked.45:00 +1:48
Free kick awarded for an unfair challenge on Craig Bryson by Corry Evans.45:00 +1:10
Free kick awarded for a foul by Paul Coutts on Robbie Brady. David Stockdale takes the direct free kick.45:00 +0:06
Ahmed Elmohamady produces a cross, Stephen Quinn has a headed effort at goal from deep inside the area missing to the left of the target.44:18
Gareth Roberts challenges David Meyler unfairly and gives away a free kick. Ahmed Elmohamady takes the free kick.42:28
Gareth Roberts restarts play with the free kick.42:28 Booking
Booking Booking for David Meyler.40:49
Unfair challenge on Will Hughes by David Meyler results in a free kick.38:34 Booking
Booking Paul Coutts receives a yellow card.36:58
Unfair challenge on Robert Koren by Craig Bryson results in a free kick. The free kick is delivered left-footed by Robbie Brady from right channel, clearance made by Richard Keogh.34:15
The ball is crossed by Robbie Brady, John Brayford makes a clearance.33:45
Unfair challenge on David Meyler by Gareth Roberts results in a free kick. Direct free kick taken by Stephen Quinn.33:24
Handball by Conor Sammon. David Stockdale takes the direct free kick.31:35
Jeff Hendrick takes a shot. Blocked by Paul McShane. Short corner taken by Paul Coutts from the right by-line.30:29
The ball is crossed by Ahmed Elmohamady, clearance by Richard Keogh.29:22
The ball is swung over by Ahmed Elmohamady, Headed effort from inside the area by Robert Koren misses to the left of the target.28:02
Free kick crossed by Ahmed Elmohamady, Conor Sammon makes a clearance.28:02 Booking
Booking Craig Bryson goes into the referee's book.27:55
Foul by Craig Bryson on David Meyler, free kick awarded.27:15
The ball is swung over by Ahmed Elmohamady, clearance made by Richard Keogh. David Meyler crosses the ball, Craig Bryson makes a clearance.25:28
A cross is delivered by Craig Bryson.23:45
Shot from outside the box by David Meyler misses to the left of the target.22:22
Robert Koren challenges Richard Keogh unfairly and gives away a free kick. Direct free kick taken by Adam Legzdins.21:17
The referee penalises Robert Koren for handball. Adam Legzdins restarts play with the free kick.20:32
Will Hughes produces a right-footed shot from just outside the box that goes wide right of the goal.18:35
Foul by Will Hughes on David Meyler, free kick awarded. Free kick taken by Stephen Quinn.17:54
Jay Simpson is caught offside. Richard Keogh takes the indirect free kick.15:34
Will Hughes concedes a free kick for a foul on Ahmed Elmohamady. Free kick taken by David Stockdale.12:56
A cross is delivered by Ahmed Elmohamady.10:59
David Meyler gives away a free kick for an unfair challenge on Gareth Roberts. Gareth Roberts takes the free kick.9:36
Unfair challenge on Craig Bryson by Corry Evans results in a free kick. Jeff Hendrick takes the free kick.7:59
Conor Sammon has an effort at goal from deep inside the area missing to the left of the goal.7:20
Foul by Stephen Quinn on Will Hughes, free kick awarded. Adam Legzdins takes the free kick.6:48
Inswinging corner taken right-footed by Robert Koren, Richard Keogh manages to make a clearance.5:53
Unfair challenge on Craig Bryson by Jay Simpson results in a free kick. Free kick taken by John Brayford.3:50
Jamie Ward gives away a free kick for an unfair challenge on Corry Evans. The free kick is delivered left-footed by Robbie Brady from right channel, Jeff Hendrick makes a clearance.3:11
Centre by Robbie Brady, John Brayford manages to make a clearance. Inswinging corner taken right-footed by Robert Koren from the left by-line, save by Adam Legzdins.2:45
Corry Evans fouled by Jamie Ward, the ref awards a free kick. Paul McShane takes the direct free kick.0:35
The ball is sent over by Ahmed Elmohamady, John Brayford makes a clearance. The ball is crossed by David Meyler, Adam Legzdins makes a save.0:00
The game begins.
Live data and text provided by our data suppliers